Chemical Immobilization of Free-Ranging Moose‪.‬

ABSTRACT: A wide range of drugs and drug combinations have been used to capture free-ranging moose (Alces alces). Currently, potent opioids are considered the drugs of choice for capture of free-ranging moose. Recommended doses are carfentanil at 0.01 mg/kg or etorphine at 7.5 mg/adult. Combining an opioid with a sedative drug like xylazine will increase the risk of bloat, regurgitation, and aspiration of rumen contents. Extreme toxicity for humans and lost darts are major concerns when using potent opioids under field conditions. The best non-opioid alternative is medetomidine at 40-50 mg/adult combined with ketamine at 600 mg/adult. Carfentanil, etorphine, and medetomidine-ketamine have wide safety margins in moose and the risk of severe anesthetic side effects in healthy animals is minimal. Chemical immobilization from a helicopter in winter is considered the best capture method for moose. Due to animal welfare considerations and a low therapeutic index, neuromuscular blocking agents should not be used in moose. A mortality rate greater than 2% during immobilization and a one month post capture period is not acceptable for routine moose captures. Key words: Alces alces, anesthesia, capture, carfentanil, etorphine, immobilization, ketamine, medetomidine, xylazine